Damper control for heat-exchange apparatus



A J. M. HARRISON.

DAMPER CUNTROL FOR HEAT EXCHANGE APPARATUS.

APPLICATION FILED APR. 17, 1919. 15592 7 1 I Patented Oct. 4, 1921.

2 SHEETSSHEET l.

J. M. HARRISON.

DAMPER CONTROL FOR HEAT EXCHANGE APPARATUS.

APPLICATION FILED APR. 17,1919.

1,39%?61. Patented 0%. 4,1921.

2 SH EETSSHEET 2.

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EL JGL M H B 1L EL jzzvezzior PATENT oaa'aea.

JAMES M. HARRISON, 0F CLEVELAND, OHIO.

' CONTROL FOR HEAT-EXCHAN GE APPARATUS.

Application filed April 17, 1919. Serial No. 290,789.

' for heating air. gas. oil or other fluids prior to their combustion in furnaces used for metallurgical or other purposes or prior to their use in chemical. drying, or other processes. or for any other purpose, as for instance the heating of air for heating and ventilating. My invention relates particularly to a system of control of the hot gases or products of combustion used for heating the air. gas or other fluids which are later to be employed for any of the purposes above mentioned.

In heat-exchange apparatus the air, gas, or other fluid which is to be heated is usually passed through a closed system of ducts or pipes constituting heat-exchange elements around the outside of which the heating fluids. usually hot gases or products of combustion. which are employed for heating the fluid within the heat-exchange elements. are made to pass. The heat-exchangeelements are generally inclosed in a duct or chamber through which the heating fluids are conducted by suitable flues.

The fluid within the heat-exchange elements which is to be heated normally flows continuously from the source of its supply to the apparatus which it serves and thereby the cast iron or other metal conduits comprising the heat-exchange elements through which the fluid passes are kept cool enough to prevent their being overheated by the heating fluids which flow over their outer surfaces.

If for any reason the flow of fluid through the heat-exchange element is interrupted. the cooling effect of this fluid is destroyed and the heat-exchange elements are liable to be damaged or even destroyed by the heat of the heating-fluids circulating about them.

It is the object of my invention to prevent such damage or destruction. To attain the object of my invention I provide a main path or flue for the heating gases through the chamber occupied by the heat-exchange Specification of Letters Patent.

conduits I provide a damper.

Patented (Oct. 41, 1921i.

elements to the waste-gas flue or chimney and a by-pass path or flue for the heating gases around the heating chamber in which .the heat-exchange elements are located.

I provide suitable pipes or conduits for conducting the heating gases through the two paths above described to the waste-gas flue or stack and in each of these pipes or I connect these two dampers by suitable means to be operated in one direction by the fluid pressure within the heat-exchange elements or the pipes or conduits leading to them and also connect the dampers to be operated in the opposite direction by a spring, weight or other suitable means opposed to the effort of the flllld pressure above referred to.

The apparatus of this part of my invention is arranged so that when there is a fluid pressure within the heat-exchange elements or in the pipes leading to them the damper in the by-pass will be closed and the damper 1n the main pipe will be opened so that the products of combustion used for heating the fluid within the heat-exchange elements will pass through the heating chamber and the fluid within the heat-exchange elements will be heated as desired. If for any reason the pressure within the heat-exchange elements is reduced below a predetermined amount, the damper in the by-pass will be opened and that in the main pipe from the heating chamber will be closed so that the heatinggases or products of combustion used for heating the fluid within the heat-exchange elements will not pass through the heating chamber. but will flow through the by-pass into the waste-gas flue or stack. The serious overheating of the heat-exchange elements is thereby prevented.

In addition to providing for the movement of the dampers by fluid pressure, I provide also thermostatic control of the dampers for regulating the temperature of the heated fluid and for protecting the heatexchange elements.

In the embodiment of my invention shown in the accompanying drawings, Figure 1 is a side view partly in section of a heating fur-- nace equipped with my control apparatus responsive to fluid pressure; Fig. 2 is a front elevation of the furnace shown in Fig. 1; Fig. 3 is a horizontal section on line IIL-III of Fig. 1; Fig. 4. is a plan of the fuce shown in Figs. 1 and 2; and Fig. 5 is a longitudinal vertical section of a furnace equipped with control apparatus responsive to both fluid pressure and temperature.

Referring to the drawings, the wall of the furnace, 1, incloses a. chamber, 2, within which there are arranged metal pipes or heat-exchange elements, 3, through which the air, gas or other fluid to be heated is made to flow. These pipes or conduits, 3, may be grouped and connected in any desired manner to secure the best results. The fluid to be heated is conducted to and from the heat-exchange elements, 3, by the pipes, 4 and 5, respectively.

Spaces, 6, are provided between the heatexchange elements, 3, through which spaces the hot gases of combustion used for heating the fluid within the heat-exchange elements flow on their way to the breeching or flue, 7, and waste-gas stack, 8. 9, is acombustion chamber below the heating chamber, 2, and 10, represents a screen or checker work through which the heating gases pass into the heating chamber.

11, is an oil or gas burner of any suitable type connected with suitable fuel and air supply pipes by means of valves, 12, and 13. 14, is a by-pass for the heating gases around the heating chamber, 2. Within the by-pass, 14. is located the valve or damper, 15, and within the breeching or flue, 7, is located the damper, 16. As shown, these dampers are connected for simultaneous operation by means of a connecting rod, 17. The damper, 16, is mounted upon and secured for rotation with the shaft, 18. The damper, 13, is mounted upon and secured for rotation with the shaft, 19. These shafts, 18 and 19, project through the walls of the fine, 7, and by-pass, 14, respectively and carry upon their projecting portions levers, 20 and 21, respectively which are keyed or otherwise secured to their shafts for rotation with them. The rod, 17, has its ends pivoted re spectively to the levers, 20 and 21. Shaft, 19, carries at its outer end another lever, 22, secured to the shaft, 19, for rotation therewith. This lever, 22, is connected for operation by a connecting rod, 23, to the diaphragm or piston-operated lever, 24. Lever, 24, ispivoted at. 25, to the diaphragmhousing, 26. Within the housing, 26, is a diaphragm or piston arranged so that when a predetermined pressure is applied to its lower surface it will raise the lever, 24, about its fulcrum, 25, and when pressure is removed from its lower surface the lever, 24, will fall .due to its own weight or any suitable means such as the weight, 27, or a spring which may be employed for this purpose.

The chamber within the housing, 26, below the actuating diaphragm or piston, is connected by means of the pipe, 28, to the intake pipe, 4, through which flows the air or other fluid to be heated. A cut-off valve, 29, may be connected in the pipe, 28, if desired. I

The operation of the apparatus above described is as follows:

The heat-exchange elements, 3, being properly connected by pipes, 4 and 5, to the source of supply and the apparatus of utilization respectively and the heating gases being supplied to the combustion chamber, 9, the valve, 29, if used, should be opened. Under these conditions the pressure within the pipe, 4, will be transmitted through pipe, 28, to the lower side of the piston or diaphragm in the housing, 26, to lift the lever, 24, and thereby close damper, 15, and open damper, 16. The heating gases will now pass from the combustion chamber, 9, upwardly through the screen, 10, and the spaces, 6, between the heat-exchange elements, 3, through the breeching or flue, 7, through the open damper, 16, to the wastegas outlet, 8. So long as pressure is main tained within the pipe, 4. thereby maintaining the pressure within the diaphragm housing, 26, the dampers will remain in the position just described. If, however, the pressure within the pipe, 4, should fail, as by reason of the stoppage of the fan or blower which creates it, the diaphragm or piston within the housing, 26, will be unsupported and will fall and the damper, 15, will be opened while the damper, 16, will be closed by the downward movement of lever, 24.

The heating gases will now pass out of combustion chamber, 9, through the by-pass, 14, to the waste-gas outlet or stack, 8, and theheat-exchange elements, 3, will not be overheated as they would be were the heating gases to continue to flow through the heating chamber after the stoppage of the flow of the air or other fluid within the heatexchange elements.

It will be observed that the dampers, 15 and 16, are connected for simultaneous operation by the same operating means and that when the damper, 15, is opening, the damper, 16, is closing, and, vice versa, when the damper. 15, is closing, the damper, 16, is opening. By substituting a spring for the weight, 27, or by otherwise varying the force which acts upon the lever, 24, in opposition to the fluid pressure within the housing, 26, a graduated movement of the dampers will occur in response to a change in the pressure within the heat-exchange elements. The dampers, 15 and 16, may therefore be so controlled as to both be held partially open under predetermined conditions, or for the one to be closed tight and the other wide open under other predetermined conditions.

It will be understood that instead of burning gas, oil or other fuel in the combustion chamber, 9, the heating chamber, 2, may be served by the gases of combustion of any available furnace such, for instance, as a heat treating furnace or any'other furnace from which the products of combustion may be diverted into the combustion chamber, 9, and thence into the heating chamber, 2, In Fig. 5 there is shown a heating furnace equipped with damper control responsive to both fluid pressure and temperature. In this illustrative embodiment of my invention the furnace itself is shown to be similar to the furnace shown in the other figures of the drawing, and the principal parts bear the same reference numerals. The parts comprising the damper controlling mechanism of Fig. 5, however, are given diflerent numerals.

Referring to Fig. 5,30 and 31, are the inlet and outlet pipes which conduct the fluid to be heated to and from the heat-exchange elements, 3. 32, is the main waste-gas pipe or flue and 33, is the by-pass for conducting the waste-gases around instead of through the heating chamber, 2. Instead of employing two dampers as shown in Figs. 1, 2, 3 and 4, I have shown a single damper, 34,

which is located at the juncture of the main and by-pass flues, and is secured to a rock shaft, 35, in such a manner that it may be made to close either flue or to stand in any intermediate position, if desired, leaving both flues partially opened. A counterbalanced lever, 36, is secured to the shaft, 35, to which the damper, 34, is also secured for rotation.

' Upon the wall or other suitable support, 37, are mounted the fulcrum bracket, 38, and two pressure operated diaphragms, 39. and 40. These diaphragms and the fulcrum bracket, 38, are in line with each other. A lever, 41, is fulcrumed upon a pivot in bracket, 38, and the operating parts of the diaphragms, 39and 40, are pivotally connected to lever, 41, at 42 and 43, respectively.

A connecting'rod, 44, has its ends pivotally connected to levers, 36 and 41, at 45 and 46, respectively. A spring, .47, is connected between the lever, 41, and the support, 37, and tends always to rock lever, 36,

and damper, 34, into the position in which I the latter closes flue, 32, and opens flue, 33.

Diaphragm, 39, is connected by a small pipe. 48, to inlet pipe. 30, and is operated by pressure within said pipe to rock the lever, 41, about its pivot in bracket, 38, to move damper, 34, so as to close the by-pass, 33. and open' the main flue, 32.

Diaphragm, 40, is connected by a small pipe, 49, to a thermostat, 50, shown inserted into pipe; 31, and is operated by pressure created by a rise in temperature in the thermostat, 50, and transmitted to diaphragm, 40, through pipe. 49. in a well known manner. Pressure within diaphragm. 40, tends to rock lever, 41, about its pivot in bracket,

.lever, 41, to cause damper, 34, to open the by-pass, 33, and close the main flue, By properly proportioning the efforts of the diaphragms, 39 and 40, and the strength of the spring, 47, the damper, 34, may be controlled to closely regulate the temperature of the fluid in the pipe, 31, or any part of the heat-exchange elements to which the thermostat may be connected, and at the same time the damper controlling apparatus will protect the heat-exchange elements from overheating if the pressure or flow of fluid in them should cease or fall below a predetermined amount or the temperature within the heat-exchange elements rise above a predetermined degree.

I have observed that in the use of fluidheating furnaces the failure of the pressure or flow of the fluid to be heated occurs at unexpected times and frequently results in serious damage to the apparatus, loss of time and expensive repairs. By the use of my invention the danger of such damage and the consequent expense and interruption of service are eliminated.

Having thus described my invention, I claim and desire to secure by Letters Patent:

1. In heat-exchange apparatus, a cham ber, heat-exchange elements in said chamber, a main flue and a bypass flue for conducting fluid respectively through and around said chamber, means for controlling the flow of fluid through said flues, and means actuated by increase of pressure in said heat-exchange elements to operate said controlling means to divert the flow of fluid from said by-pass flue to said main flue.

2. In heat-exchange apparatus, a chamber, heat-exchange elements in said chamber, a main flue and a by-pass flue for conducting fluid respectively through and around said chamber, means for controlling the flow of fluid through said flues, means responding to increase of temperature in said heat-exchange elements to operate said controlling means to divert the flow of fluid from said main flue to said by-pass flue and means actuated by pressure in said heat exchange elements to operate said controlling means to divert the flow of fluid from said by-pass flue to said main flue.

3. In heat-exchange apparatus, a chamber, heat-exchange elements in said chamber, a main flue and aby-pass flue for conducting fluid respectively through and around said chamber, means for controlling the flow of fluid through said fines, and means responding to decrease of pressure or increase of temperature or both in said heat- 4. In heat-exchange apparatus, a cham-' ber, heat-exchange elements in said chamber, a main flue and a. by-pass flue for conducting fluid respectively through and around said chamber, means for controlling the flow of fluid through said flues, means actuated by pressure in said heat-exchange elements to operate said controlling means to permit the flow of fluid through said chamber and to prevent the flow of fluid through said by 'pass flue,and other means opposed to said pressure-actuated means adapted upon the failure of pressure in said heatexchange elements to operate said controlling means to prevent the flow of fluid through said chamber and to permit the flow of fluid through said by-pass flue.

5. In heat-exchange apparatus, a chamber, heat-exchange elements in said chamber, a main flue and a by-pass flue 'for conducting fluid respectively through and around saidchamber, means for controlling the flow of fluid through-said flues, actuating means responding to increase of temperature in said heat-exchange elements to operate said controlling means to divert the flow of fluid from said main flue to said bypass flue, means actuated by pressure in said heat-exchange elements to operate said controlling means to divert the flow of fluid from said by-pass flue to said main flue, and yielding means for normally holding said controlling means in position to permit the flow of fluid through said by-pass flue and prevent its flow through said main flue.

6. In heat-exchange apparatus, a chamber, heat-exchange elements in said chamber, a main flue and a by-pass flue for conducting fluid respectively through and around said chamber, means for controlling the flow of fluid through said flues actuating means responding to increase of pressure in said heat-exchange elements to operate said controlling means to divert-the flow of fluid from said by-pass flue to said main flue, and yielding means opposed to said pressure-responsive means for operating said controlling means to divert the flow of fluid from said main flue to said bypass flue.

7. In heat-exchange apparatus in which there is an exchange of heat between two fluids, one of which is caused to flow through the interior and the other of which is caused to flow over the exterior of heat-exchange elements, heat-exchange elements, means for causing fluid to flow through the interior of said elements, means for causing fluid to flow over the exterior of said elements, and means responding to decrease of pressure in that fluid to which heat is being imparted, to divert from said heat-exchange elements the flow of that fluid from which heat is being extracted.

8. In heat-exchange apparatus in which there is an exchange of heat between two fluids one of which is caused to flow through the interior and the other of which is caused to flow over the exterior of heat-exchange elements, heat exchange elements, means for causing fluid to flow through the interior of said elements, means for causing fluid to flow over the exterior of said elements, means responding to increase vof temperature of that fluid to which heat is being imparted to divert from said heat-exchange elements the flow of that fluid from which heat is being extracted, and means responding to increase in pressure of that fluid to which heat is being imparted to direct toward said heat-exchange elements the flow of that fluid from which heat is being extracted.

9. In heat-exchange apparatus in which there is an exchange of heat between two fluids one of which is caused to flow through the interior and the other of which is caused to flow over the exterior of heat exchange elements, heat exchange elements, means for causing fluid to flow through the interior of said elements, means for causing fluid to flow over the exterior of said elements and means responding to decrease of pressure or increase of temperature or both of that fluid to which heat is being imparted to divert from said heat exchange elements the flow of that fluid from which heat is-being extracted.

In testimony whereof I afix my signature in the presence of two witnesses.

JAMES M. HARRISON. 

